One other possibility: decouple the gui from both Python and pip releases by packaging and, at least initially, releasing it through PyPI as an independent project.  That is, after all, the preferred mechanism for adding new functionality to the standard library.  The only thing that would need to be in the standard library then is an IDLE version of "ensuregui", serving the same purpose as "ensurepip", to provide an easy way for IDLE users to initially install the gui using pip and PyPI.  If, down the road, the gui is a success and the long-term support issues can be addressed, bringing the gui directly under the pip project could happen in the future.